examples: improve counter_without_macros (#751)

examples/counter_without_macros/src/lib.rs

@@ -1,48 +1,44 @@
 use leptos::{ev, html::*, *};
 
-pub struct Props {
-    /// The starting value for the counter
-    pub initial_value: i32,
-    /// The change that should be applied each time the button is clicked.
-    pub step: i32,
-}
-
 /// A simple counter view.
-pub fn view(cx: Scope, props: Props) -> impl IntoView {
-    let Props {
-        initial_value,
-        step,
-    } = props;
+// A component is really just a function call: it runs once to create the DOM and reactive system
+pub fn counter(cx: Scope, initial_value: i32, step: i32) -> impl IntoView {
     let (value, set_value) = create_signal(cx, initial_value);
 
+    // elements are created by calling a function with a Scope argument
+    // the function name is the same as the HTML tag name
     div(cx)
-        .child((
-            cx,
+        // children can be added with .child()
+        // this takes any type that implements IntoView as its argument
+        // for example, a string or an HtmlElement<_>
+        .child(
             button(cx)
+                // typed events found in leptos::ev
+                // 1) prevent typos in event names
+                // 2) allow for correct type inference in callbacks
                 .on(ev::click, move |_| set_value.update(|value| *value = 0))
-                .child((cx, "Clear")),
-        ))
-        .child((
-            cx,
+                .child("Clear"),
+        )
+        .child(
             button(cx)
                 .on(ev::click, move |_| {
                     set_value.update(|value| *value -= step)
                 })
-                .child((cx, "-1")),
-        ))
-        .child((
-            cx,
+                .child("-1"),
+        )
+        .child(
             span(cx)
-                .child((cx, "Value: "))
+                .child("Value: ")
+                // reactive values are passed to .child() as a tuple
+                // (Scope, [child function]) so an effect can be created
                 .child((cx, move || value.get()))
-                .child((cx, "!")),
-        ))
-        .child((
-            cx,
+                .child("!"),
+        )
+        .child(
             button(cx)
                 .on(ev::click, move |_| {
                     set_value.update(|value| *value += step)
                 })
-                .child((cx, "+1")),
-        ))
+                .child("+1"),
+        )
 }

examples/counter_without_macros/src/main.rs

@@ -1,16 +1,8 @@
-use counter_without_macros as counter;
+use counter_without_macros::counter;
 use leptos::*;
 
 pub fn main() {
     _ = console_log::init_with_level(log::Level::Debug);
     console_error_panic_hook::set_once();
-    mount_to_body(|cx| {
-        counter::view(
-            cx,
-            counter::Props {
-                initial_value: 0,
-                step: 1,
-            },
-        )
-    })
+    mount_to_body(|cx| counter(cx, 0, 1))
 }